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The explanation for the lift is not correct. Bernoulli's equation is true, but the longer upper surface does not explain the increased speed of air.

A wing is just deflecting air particles down (both upper and lower surfaces contribute to this), so the wing must go up.

Typical wing shape, as seen in fig 3 also, is designed to minimize the drag and turbulent airflows around it, while deflecting as much air as possible (or needed). Making one surface longer than the other is not the target.

The commonly used term for the lift (bird, airplane, frisbee, boomerang) effect is the Bernoulli principle.

In a short one-page, how-to column (with 14 illustrations) there's no room to bring up: the angle of attack, the Coanda effect, reducing the strength of turbulence with flaps, how airplanes can fly upside down, how sailboats use the "Tacking technique" to sail into the wind, curveballs and how Beckham "bends it."

The fundamentals won't please everyone but they open the door to investigate more.

Pnu is correct: I can't believe Ty has dragged out these old cliches; blowing across a piece of paper demonstrates the Coanda effect, not Bernoulli's principle (It is the curvature of the paper, not the faster flow of air, which makes it lift; it is only coincidence that gravity supplies a curve which appears to support Bernoulli. Try turning the paper strip on its side, so that it does not curve. There will be no movement towards the air stream).

Second, the molecules which travel above a wing have no "memory" thus have no idea they have farther to travel. There is no "rejoining" of air molecules at the trailing edge of the wing--there never was. This concept is in many aerodynamics books--but not any recent ones! Typical way to see the error of this view is to think about planes which fly upside down--Ty's explanation cannot explain this; pnu is accurate.

Posted by
kiteship on July 29, 2007 at 18:48:29 Pacific Time

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